Straightening apparatus for elongated tubular and rod stock

ABSTRACT

A straightening pass in an apparatus for straightening of elongated tubular or rod stock has a concave skew roll and a composite second skew roll located opposite the concave roll with reference to the center line of the pass. The second skew roll has a driven median section provided with two coaxial trunnions and two outer sections each of which has a disk eccentrically mounted on a trunnion and a stock-engaging ring which is rotatable on the respective disk. The disks are angularly adjustable on their trunnions and are adjustably coupled to a holder for the second skew roll. The rings can be rotated in response to rotation of the median section by providing them with internal gears which receive torque from gears provided on the respective trunnions.

United States Patent" [1 1 Hartkopf July 24, 1973 STRAIGHTENING APPARATUS FOR ELONGATED TUBULAR AND ROD STOCK [75] lnventor: Heinz Hartkopf, Solingen, Germany [73] Assignee: TheKieserling & Albrecht, Solingen,

Germany [22] Filed: Mar. 16, 1972 [21] Appl. No.: 235,298

[30] Foreign Application Priority Data Mar. 22, 1971 Germany P 21 13 713.3

[52] US. Cl. 72/99 [51] Int. Cl B21d l/02 [58] Field of Search 72/99, 162

[56] References Cited UNITED STATES PATENTS 2,438,240 3/1948 Trudeau 72/99 3,626,732 12/1971 Krafft et al. 72/99 Primary Examiner-Milton S. Mehr Att0rneyMichael S. Striker [57] ABSTRACT A straightening pass in an apparatus for straightening of elongated tubular or rod stock has a concave skew roll and a composite second skew roll located opposite the concave roll with reference to the center line of the pass. The second skew roll has a driven median section provided with two coaxial trunnions and two outer sections each of which has a disk eccentrically mounted on a trunnion and a stock-engaging ring which is rotatable on the respective disk. The disks are angularly adjustable on their trunnions and are adjustably coupled to a holder for the second skew roll. The rings can be rotated in response to rotation of the median section by providing them with internal gears which receive torque from gears provided on the respective trun- 12 Claims, 5 Drawing Figures PATENHL JUL 24am SHEET 2 0F 3 FlG.3

FIGA

PATENIED W 3.747. 386

sum 3 BF 3 FIG.5

STRAIGHTENING APPARATUS FOR ELONGATED TUBULAR AND ROD STOCK BACKGROUND OF THE INVENTION The present invention relates to improvements in apparatus for straightening of elongated tubular or rod stock. More particularly, the invention relates to improvements in so-called straightening passes which are groups of at least two straightening rolls clustered around a center line which coincides with the axis of the stock while the stock is being treated by the rolls. Still more particularly, the invention relates to im provements in straightening passes which employ preferably concave skew rolls, i.e., concave rolls whose axes are inclined with reference to the center line of the pass.

The presently known straightening apparatus which employ one or more passes and wherein each pass comprises two skew rolls must be equipped with supporting and guiding rollers for tubular or rod stock and/or with so-called straightedges or rulers all of which serve to insure proper radial guidance and support for the stock during treatment. The friction between a ruler and the stock is very high so that the ruler is subjected to considerable wear. Furthermore, the friction between one or more rulers and the stock necessitates the use of powerful motors which rotate the skew rolls, and the rulers are likely to scratch or otherwise deface the stock, especially if the material of the stock is relatively soft. It was already proposed to employ rulers which consist of relatively soft material, such as certain types of synthetic plastic substances. However, the useful life of soft rulers is extremely short, i.e., they must be replaced at very frequent intervals with attendant losses in output of the straightening apparatus.

British Patent No. 578,747 discloses a skew-rolling apparatus which operates without rulers and wherein each pass comprises three concave skew rolls which are grouped around the center line of the respective pass. One skew roll of each pass is driven and is mounted at a fixed distance from the center line. The other two rolls of each pass are adjustable radially of the center line and are pivotable with their holders. Such apparatus are quite complicated and expensive; in addition, nearly all of the stresses which develop in the course of a straightening operation are transmitted to guide means for the adjustable skew rolls.

Another straightening apparatus which operates without rulers is disclosed in German Patent No. 392,028. This apparatus employs one or more pairs of straightening rolls and the rolls of each pair alternate with supporting rollers for tubular or rod stock. A

drawback of such apparatus is that they cannot be used for straightening of small-diameter stock because the supporting rollers and their holders occupy so much room that they cannot be placed sufficiently close to the center line of the pass. Furthermore, the stresses which are transmitted to the supporting rollers and to the adjusting mechanism for straightening rolls are extremely high.

SUMMARY OF THE INVENTION An object of the invention is to provide a straigthening apparatus with a novel and improved pass which can treat elongated tubular or rod stock without resorting to discrete supporting or guide rollers and/or rulers, and which can be conveniently and rapidly adjusted to treat small-diameter, medium-diamter or largediameter stock with the same degree of accuracy.

Another object of the invention is to provide a novel and improved straightening pass which may but need not employ more than two skew rolls and wherein the adjustment of certain portions of a single skew roll suffices to convert the pass from streatment of largerdiameter stock to treatment of smaller-diameter stock or vice versa.

A further object of the invention is to provide a straightening pass with preferably two skew rolls wherein the two rolls suffice to insure satisfactory straightening as well as proper support for elongated tubular or rod stock.

An additional object of the invention is to provide a straightening pass with a novel and improved skew roll.

The invention is embodied in a straightening appara tus for elongated tubular or rod stock which comprises a straightening pass having a center line located in the path for the stock and including a plurality of skew rolls whose axes are inclined with reference to the center line. One of the skew rolls comprises a plurality of sections including a first section which is preferably the median section of three sections and at least one additional or second section which is eccentric with reference to the first section and is movable about an axis which is parallel to the axis of the first section to thereby convert the pass for treatment of largeror smaller-diameter stock. If the pass comprises two skew rolls, they are preferably located diametrically opposite each other with reference'to the center line. If the one skew roll comprises two second sections, they preferably flank the first section and are preferably mounted on coaxial trunnions of the first seciton. Each second section preferably comprises a substantially diskshaped inner annular member which is eccentrically mounted on the respective trunnion and is adjustably coupled to the holder for the one skew roll, and a ringshaped outer annular member which is rotatable on and surrounds the inner annular member. The axes of the two disk-shaped annular members are located at the opposite sides of the common axis of the trunnions, and the outer annular members are preferably provided with conical external stock-engaging surfaces whose diameters decrease in directions toward the first section of the one skew roll.

.The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved straightening apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of a single pass in a I straightening apparatus which embodies one form of the invention;

FIG. 2 is a horizontal sectional view as seen in the direction of arrows from the line II-II of FIG. 1;

FIG. 3 is an end elevational view of the upper straightening roll, as viewed from the right-hand side of FIG. 1, and a sectional view of the lower straightening roll as seen in the direction of arrows from the line III- III of FIG. 4;

FIG. 4 is a composite sectional view as seen in the direction of arrows from the line IV-IV of FIG. 3; and

FIG. is a fragmentary partly elevational and partly axial sectional view of a straightening roll constituting a modification of the roll shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIG. 1, there are shown two skew rolls 1 and 2 of a pass in a straightening machine for elongated tubular or rod stock 3 of circular crosssectional outline. The rolls 1 and 2 are disposed substantially diametrically opposite each other with reference to the center line of the pass and their axes of rotation are respectively indicated at 1a and 2a. Such axes are inclined with reference to the center line of the pass. The roll 1 is a customary concave skew roll whereas the roll 2 comprises three sections which are adjacent to each other, as considered in the direction of the axis 2a, and are respectively denoted by the characters 4, 5 and 6. The axial length of each of the three sections 4-6 is at least substantially the same. The two outer sections 4 and 6 flank the median section 5 and are respectively turnable on coaxial trunnions 5a, 5b provided at the respective axial ends of the median section 5. The axes of the outer sections 4 and 6 are respectively shown at 4a and 6a; it will be noted that these axes are located at the opposite sides of the common axis (2a) of the trunnions 5a and 5b.

The two outer sections 4, 6 of the straightening roll 2 respectively comprise eccentrically mounted inner annular members or disks 7, 8 (FIG. 4) and hollow frustoconical outer annular members or rings 13, 14 which coaxially surround the respective disks 7, 8 and are rotatable about the axes 4a, 6a of the respective sections 4, 6. Antifriction bearings 9, 10 and 1 1, 12 are respectively interposed between the annular members 7, l3 and 8, 14 of the sections 4 and 6. The disks 7, 8 are respectively screwed, bolted or otherwise fixedly secured to disk-shaped flanges 15, 16 which, in turn, are respectively fixedly secured to axially parallel bolts or posts 17, 18. These posts 17 and 18 are respectively parallel to the axes 4a and 6a of the sections 4, 6. Those portions of the posts 17, 18 which extend outwardly beyond the respective flanges 15, 16 (i.e., in directions away from the median section 5) rotatably support threaded adjusting and coupling elements in the form of screws 19, 20. It will be noted that the axes of the screws 19, 20 are respectively normal to the axes of the posts 17, 18. The screws 19, 20 carry spherical joints (see the joint 19a of FIG. 3) which are spaced from the respective posts 17, 18 and are turnably received in suitable sockets provided therefor in projecting portions 21, 22 of a holder 23 for the straightening roll 2. As shown in FIG. 3, the screw 19 carries two lock nuts 19b, 190 which flank the spherical joint 19a and can be adjusted axially of the screw 19 to thereby change the angular position of the disk 7. Once the disk 7 is moved to the desired angular position relative to the trunnion 5a of the median roll section 5, the nuts 19b, 190 are moved toward each other to thereby lock the disk 7 in such selected position. The screw 20 carries two similar nuts (not shown) which enable the operator to change the angular position of the disk 8 relative to the trunnion 5b of the median section 5. The just described adjusting means for the angular positions of the disks 7 and 8 enable the operator or operators to accurately select the positions of the axes 4a, 6a relative to the center line of the stock 3 so that the rolls 1 and 2 can be used for straightening of largeror smaller-diameter stock. The external surface of such stock is engaged by the conical external surfaces of the rings 13 and 14; these surfaces taper toward the section 5.

In order to reduce or eliminate friction between the stock 3 and the external surfaces of the rings 13 and 14 irrespective of the nature of material of which the stock is made, the rings may be driven in a manner shown in FIG. 5. The ring 13 of FIG. 5 surrounds a two-piece eccentric disk whose portions are shown at 24 and 25. These portions are secured to each other by means of at least one distancing screw or bolt (not shown) in such a way that they define therebetween a chamber or compartment for two gears 27, 28 which are mounted on a shaft 27. The portion 24 of the disk carries a shaft 29 for an intermediate gear 30 which is rotatably supported thereon. The intermediate gear 30 meshes with the gear 28 on the shaft 26 and with a further gear 31 which is fixedly secured to the trunnion 5a of the median roll section 5. When the median section 5 is rotated in the direction indicated by the arrow 32 (FIG. 3), the aforedescribed gear train 27, 28, 30, 31 causes the ring 13 to rotate in the same direction. This is due to the fact that the gear 27 which receives torque from the gear 28 meshes with an internal gear 13a of the ring 13. The shaft 26 is journalled in the portions 24, 25 of the disk and carries a key 26a which drives the gear 27 in response to rotation of the gear 28. The means for driving the median section 5 of the roll 2 includes a flange 40 which is secured to an extension of the trunnion 5b (see FIG. 4) and receives motion from a motor (not shown) through the intermediary of a suitable variable-speed transmission. The means for rotating the concave skew roll 1 (see the arrow 33 in FIGS. 1 and 3) is of conventional design and is not shown in the drawing. When the rolls 1 and 2 are driven, the stock 3 is caused to move lengthwise in the direction indicated by arrow 34. The means by which the ring 14 on the disk of the section 6 of the roll 2 can be driven to rotate in the same direction as the median section 5 is preferably indentical with the means shown in FIG. 5 for driving the ring 13.

Referring to FIG. 2, it will be seen that the stock 3 is properly engaged and supported by the conical external surfaces of the rings 13, 14 of the composite roll 2 and by the adjoining portions of the concave peripheral surface on the one-piece skew roll 1. The stock 3 is caused to move lengthwise (arrow 34) and to simultaneously rotate about its own axis, i.e., along the center line of the pass formed by the straightening rolls 1 and 2.

An important advantage of the improved two-roll straightening pass is that it can operate properly without resorting to discrete supporting and guiding rollers as well as without the aforediscussed rulers which are subject to wear and are likely to scratch or otherwise damage the stock. Furthermore, the adjustments in the angular positions of the disk-shaped inner annular members of the outer sections of the composite skew roll can be completed with little loss in time so that the pass can be rapidly converted from treatment of smaller-diameter workpieces to treatment of larger'diameter workpieces or vice versa. It was found that the improved pass can be used for straightening of tubes or rods with extremely small outer diameters.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

l' claim:

1. in a straightening apparatus for elongated tubular or rod stock, a straightening pass having a center line and including a plurality of skew rolls whose axes are inclined with reference to said center line, one of said skew rolls comprising a plurality of sections including a first section whose axis coincides with the axis of said one skew roll and at least one second section which is eccentric with reference to said first section and is movable about an axis which is parallel to the axis of said one skew roll.

2. A pass as defined in claim 1, wherein another of said skew rolls is located substantially diametrically opposite said one skew roll with reference to said center line.

3. A pass as defined in claim 1, wherein said one skew roll comprises two second sections which flank said first section.

4. A pass as defined in claim 3, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising an inner annular member rotatably mounted on the respective trunnion and an outer annular member surrounding the respective inner member.

5. A pass as defined in claim 4, wherein each of said inner annular members is a disk whose axis is parallel to the axis of the respective trunnion and each of said outer annular members is a stock-engaging ring which is rotatable about the respective disk and is coaxial therewith.

6. A pass as defined in claim 3, further comprising a holder rotatably supporting said one skew roll, and adjusting means mounted on said holder and adjustably coupled with said second sections.

7. A pass as defined in claim 6, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising a disk rotatably mounted on the respective trunnion and having an axis which is parallel to the axis of said one skew roll, said adjusting means comprising threaded members articulately connected with said holder and adjustably coupled with said disks.

8. A pass as defined in claim 3, wherein each of said second sections comprises an inner annular member which is turnable relative to said first section about an axis parallel to the axis of said first section and an outer annular member which is coaxial with and surrounds said inner annular member, and further comprising means for rotating said outer annular members in a predetermined direction.

9. A pass as defined in claim 8, wherein said means for rotating said outer annular members comprises internal gears provided in said outer annular members, means for rotating said first section in said predetermined direction, second gears secured to said first section, and additional gear means arranged to transmit torque from said second gears to said internal gears in response to rotation of said first section.

10. A pass as defined in claim 9, wherein said additional gear means are mounted in the respective inner annular members.

11. A pass as defined in claim 3, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising an inner annular member rotatably mounted on the respective trunnion and having an axis which is parallel to the common axis of said trunnions, and an outer annular member which surrounds the re spective inner annular member and has a conical external stock-engaging surface.

12. A pass as defined in claim 11, wherein said outer annular members are coaxial with the respective inner annular members and the diameters of said external surfaces decrease in directions toward said first section, the axes of said inner annular sections being disposed at the opposite sides of the common axis of said trunnions. 

1. In a straightening apparatus for elongated tubular or rod stock, a straightening pass having a center line and including a plurality of skew rolls whose axes are inclined with reference to said center line, one of said skew rolls comprising a plurality of sections including a fIrst section whose axis coincides with the axis of said one skew roll and at least one second section which is eccentric with reference to said first section and is movable about an axis which is parallel to the axis of said one skew roll.
 2. A pass as defined in claim 1, wherein another of said skew rolls is located substantially diametrically opposite said one skew roll with reference to said center line.
 3. A pass as defined in claim 1, wherein said one skew roll comprises two second sections which flank said first section.
 4. A pass as defined in claim 3, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising an inner annular member rotatably mounted on the respective trunnion and an outer annular member surrounding the respective inner member.
 5. A pass as defined in claim 4, wherein each of said inner annular members is a disk whose axis is parallel to the axis of the respective trunnion and each of said outer annular members is a stock-engaging ring which is rotatable about the respective disk and is coaxial therewith.
 6. A pass as defined in claim 3, further comprising a holder rotatably supporting said one skew roll, and adjusting means mounted on said holder and adjustably coupled with said second sections.
 7. A pass as defined in claim 6, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising a disk rotatably mounted on the respective trunnion and having an axis which is parallel to the axis of said one skew roll, said adjusting means comprising threaded members articulately connected with said holder and adjustably coupled with said disks.
 8. A pass as defined in claim 3, wherein each of said second sections comprises an inner annular member which is turnable relative to said first section about an axis parallel to the axis of said first section and an outer annular member which is coaxial with and surrounds said inner annular member, and further comprising means for rotating said outer annular members in a predetermined direction.
 9. A pass as defined in claim 8, wherein said means for rotating said outer annular members comprises internal gears provided in said outer annular members, means for rotating said first section in said predetermined direction, second gears secured to said first section, and additional gear means arranged to transmit torque from said second gears to said internal gears in response to rotation of said first section.
 10. A pass as defined in claim 9, wherein said additional gear means are mounted in the respective inner annular members.
 11. A pass as defined in claim 3, wherein said first section comprises a pair of coaxial trunnions, one for each of said second sections, each of said second sections comprising an inner annular member rotatably mounted on the respective trunnion and having an axis which is parallel to the common axis of said trunnions, and an outer annular member which surrounds the respective inner annular member and has a conical external stock-engaging surface.
 12. A pass as defined in claim 11, wherein said outer annular members are coaxial with the respective inner annular members and the diameters of said external surfaces decrease in directions toward said first section, the axes of said inner annular sections being disposed at the opposite sides of the common axis of said trunnions. 